A variety of underwater signaling devices are well-known. They address the need to communicate between divers using self contained underwater breathing apparatus, commonly known as "scuba."
Most known signaling devices include some type of electronic or mechanical device for causing vibration of a diaphragm, bell or horn. Despite the many known devices, existing devices have failed to solve all of the problems associated with underwater communication, and many of the devices have introduced additional problems.
Complexity, and associated financial costs, have prevented many devices from becoming widely used. Complex devices are based on both electronic and mechanical technologies. Complex devices also suffer from a correspondingly greater parts-counts and failure rates.
The need to modify equipment has also prevented some signaling devices from becoming popular. For example, signaling devices based on compressed air from the scuba tanks may require some type of Y-connector be added to an air hose. This type of modification is not popular, particularly since it could result in increased chances of the failure of the scuba device.
Other devices have buoyancy problems, and may result in adjustments being required to a diver's weight belt. Such devices may also be bulky and awkward to transport.
What is needed is a simple underwater signaling device that is usable from the surface or by a diver, for signaling an underwater diver. The device should be simple and mechanical, should have a dependable mechanism, and should be easily operated.